perf: bypass wrappers for classless native components

CONTEXT.md

@@ -118,6 +118,8 @@ Metro integration:
 - `withUniwindConfig(config, uniwindConfig)` patches Metro graph support for uncached modules.
 - Metro adds `css` as source extension and removes it from asset extensions.
 - Metro transformer handles the configured CSS entry file specially.
+- `experimental.optimizeClasslessComponents` (off by default) compiles classless native elements
+  to raw React Native components; styled or uncertain references keep existing wrappers.
 - Metro transformer worker selection is lazy, cached per Expo/non-Expo config type, and follows Expo transformer paths or Expo-specific config markers.
 - Native platform CSS transforms into a JS module that calls `Uniwind.__reinit(...)`.
 - Web platform CSS transforms into CSS plus web runtime setup.

PR.md

@@ -0,0 +1 @@
+Litwo! Ojczyzno moja! ty jesteś jak zdrowie;

packages/uniwind/build.config.ts

@@ -51,6 +51,11 @@ export default defineBuildConfig({
             input: './src/bundler/adapters/metro/transformer.ts',
             name: 'metro/transformer',
         },
+        {
+            builder: 'rollup',
+            input: './src/bundler/adapters/metro/babel-transformer.ts',
+            name: 'metro/babel-transformer',
+        },
         {
             builder: 'mkdist',
             input: './src/bundler/adapters/metro',

packages/uniwind/jest.config.native.js

@@ -8,6 +8,7 @@ export default {
     ],
     moduleNameMapper: {
         '^react-native$': '<rootDir>/../../node_modules/react-native',
+        '^yaml$': '<rootDir>/../../node_modules/yaml/dist/index.js',
         '^@/(.*)$': '<rootDir>/src/$1',
     },
 }

packages/uniwind/src/bundler/adapters/metro/babel-transformer.ts

@@ -0,0 +1,62 @@
+import type {
+    BabelTransformer,
+    BabelTransformerArgs,
+} from 'metro-babel-transformer'
+import { componentTransform } from './component-transform'
+import {
+    TRANSFORM_COMPONENTS,
+    UPSTREAM_BABEL_TRANSFORMER,
+} from './constants'
+
+type BabelTransformerModule = BabelTransformer & {
+    default?: BabelTransformer
+}
+
+const transformerCache = new Map<string, BabelTransformer>()
+
+const getTransformer = (transformerPath: string) => {
+    const cached = transformerCache.get(transformerPath)
+    if (cached) {
+        return cached
+    }
+
+    const module = require(transformerPath) as BabelTransformerModule
+    const transformer = typeof module.transform === 'function'
+        ? module
+        : module.default
+
+    if (!transformer || typeof transformer.transform !== 'function') {
+        throw new Error(`Uniwind: Invalid upstream Babel transformer at ${transformerPath}`)
+    }
+
+    transformerCache.set(transformerPath, transformer)
+
+    return transformer
+}
+
+export const transform = (args: BabelTransformerArgs) => {
+    const customOptions = args.options.customTransformOptions ?? {}
+    const upstreamPath = customOptions[UPSTREAM_BABEL_TRANSFORMER]
+
+    if (typeof upstreamPath !== 'string') {
+        throw new Error('Uniwind: Missing upstream Babel transformer path')
+    }
+
+    const {
+        [TRANSFORM_COMPONENTS]: shouldTransform,
+        [UPSTREAM_BABEL_TRANSFORMER]: _upstreamPath,
+        ...upstreamCustomOptions
+    } = customOptions
+    const transformer = getTransformer(upstreamPath)
+
+    return transformer.transform({
+        ...args,
+        options: {
+            ...args.options,
+            customTransformOptions: upstreamCustomOptions,
+        },
+        plugins: shouldTransform
+            ? [...args.plugins ?? [], componentTransform]
+            : args.plugins,
+    })
+}